RadioBanter - View Single Post - What's in a "wall wart" so-called "transformer"?

[email protected] · September 23rd 06, 04:55 PM posted to rec.radio.amateur.homebrew

wrote:
I have a collection of "wall wart" (others may call them "transformers")
and I'd like to use one to cobble a little power supply. I've never
opened any to see what's really in them (and suspect it'll be quite a
chore), but I'm quite sure they are not ALL "transformers", because some
claim AC and some claim DC output, yet the first I grabbed out of the
junkbox claimed DC AND ALSO provided a HEALTHY AC output on the same
two wires! Furthermore, NONE of them seem to be voltage regulated!
(But if one says "X volts at Y milliamps", then loading it to Y mils
usually gives an output close to X volts.)

So what IS in them? Do the really light-weight ones, for example,
use a capacitor for relatively low-loss voltage dropping? And
why would one give *BOTH* AC and DC? Bad diode(s)?

--
--Myron A. Calhoun.
Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge
NRA Life Member and Rifle, Pistol, & Home Firearm Safety Certified Instructor
Certified Instructor for the Kansas Concealed-Carry Handgun license

It depends...

The AC ones are just a transformer.

The DC ones contain a transformer and diode(s).

The cheapies usually don't contain any capacitors or regulators, hence
there is significant AC on the DC.

--
Jim Pennino

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